The International Organization for Standardization (ISO) has promulgated a standardized system for a conventional picture compression system called Joint Photographic Expert Group (JPEG). This system provides optimal encoding or decoding of pictures by applying a Discrete Cosine Transformation (DCT) to an image to transform that image into DCT coefficients. This system works most efficiently when a relatively large number of bits are to be employed to represent the encoded information. However, if the number of bits to be employed to represent the encoded information is less than a certain predetermined value, block distortion inherent in such a DCT transform becomes prevalent enough to deteriorate the quality of the picture which may be noticed by a viewer.
In response to these deficiencies of the JPEG and DCT procedure, a new Iterated Function System (IFS) picture compression technique has been proposed, and is beginning to gain favor. This IFS technique exploits self-similarity between portions of pictures and is based on fractal geometry. IFS works on the assumption that various portions of a particular picture are analogous, even though they may be of a different size, position, perspective, or orientation. IFS utilizes this redundancy in pictures to efficiently encode the picture without resulting block distortion, as may be generated in the JPEG system. Therefore, IFS is not nearly as dependent upon the number of bits to be used to represent the encoded information, and therefore the resolution during decoding does not suffer when a relatively smaller number of bits are to be used to represent the encoded information.
The basic structure of IFS is set forth in Arnaud E. Jaquin's thesis entitled "Image Coding Based on a Fractal Theory of Iterated Contractive Image Transformations", IEEE Transactions on Image Processing, Vol. 1, No. 1, pp. 18-30), and is further set forth in U.S. Pat. Nos. 5,347,600; 5,065,447 and 4,941,193, all issued to Barnsley et al. The encoding and decoding devices as generally set forth in these references will now be described with reference to prior art FIGS. 11 and 12.
Referring first to FIG. 11, the operation of an encoding device according to the prior art is shown. As is set forth in FIG. 11, an original picture 300 is entered to a block generating circuit 200 and is therein split into a plurality of blocks 301. All of blocks 301 together cover the entire original picture 300, but do not overlap with each other. Original picture 300 is also forwarded to reduced picture generating circuit 202. A picture 307 having a reduced size, such as by way of a reduction scheme as is known in the art which is obtained through the processing of reduced picture generating circuit 202 is forwarded and stored within reduced picture storage circuit 204.
Each of blocks 301 is forwarded to a proximate area search circuit 201 which searches reduced size picture 307 stored in reduced picture storage circuit 204 to determine whether any portions of the reduced size picture are analogous to the particular block 301 being searched. As noted above, this search includes searching for portions of reduced size picture 307 which are of different size, position, perspective, or orientation than the block 301 being searched. In accordance with the detected result indicating a successful search for a most similar portion, similar block position information 306, which specifies the position of the selected portion 305 within the reduced size picture 307 that is to be extracted, is transmitted to reduced picture storage circuit 204. Thus, in accordance with these instructions, selected portion 305 of the reduced size picture 307 stored within reduced picture storage circuit 204 is extracted, and is transmitted to a rotation/inversion/level value conversion circuit 203.
Within rotation/inversion/level value conversion circuit 203, portion 305 of reduced size picture 307 is processed by a rotation/inversion/level value transformation in accordance with transformation parameters 304 which are supplied from proximate area search circuit 201. These transformation parameters 304 are indicative of the transformation which must be performed in order to transform portion 305 of reduced size picture 307 into block 301. These parameters are determined when a particular portion 305 of reduced size picture 307 is found to most closely correspond to block 301 being searched. Upon transformation at rotation/inversion/level value conversion circuit 203, a transform reduced-size picture 303 is forwarded to proximate area search circuit 201. There as a result, transformation parameters 304 and similar block position information 306 are output as ISF codes 302. Thus, a first picture is input to the system, and the output includes at least transformation parameters, for transforming a first block into a second similar block, and position information, for determining the position of the second block within the encoded picture.
Referring next to FIG. 12, a decoding apparatus is provided in which the IFS codes, including transformation parameters and similar block position information 302 which are output by the encoding device of FIG. 11, are entered into and stored in an IFS code storage circuit 205. IFS codes 302 are then sequentially read out from IFS code storage circuit 205 for each block, and are forwarded to an IFS code read out circuit 206. IFS code read out circuit 206 divides the codes into similar block position information 306 and transformation parameters 304 as provided by the encoder. Similar block position information 306 is then forwarded to reduced picture storage circuit 204 in order to reproduce the area of the reduced-size picture specified by similar block position information 306. The portion 305 of the reduced size picture stored in reduced picture storage circuit 204 corresponding to the specified area is then transmitted to a rotation/inversion/level value conversion circuit 203, and is transformed in accordance with transformation parameters 304 which are supplied from IFS code read out circuit 206. The resulting transformed picture 303 forwarded from rotation/inversion/level conversion circuit 203 is stored within decoded picture storage circuit 208. This procedure is performed for each block in the picture for which IFS codes are provided.
After all of the IFS codes for all of the blocks have been read out, IFS read out circuit 206 sends a READ OUT END notification signal 310 to duplication control circuit 207. Duplication control circuit 207 counts the number of recursive decoding/duplicating operations that have been executed, and if this count has not reached a predetermined value, duplication control circuit 207 sends a reprocessing command signal 309 to IFS code read out circuit 206 in order to continue execution of decoding processing for all of the blocks in the picture according to a recursive decoding procedure. Simultaneously, the reprocessing command information is sent via control signal 311 to a switch 209 in order to send partially decoded picture 313 to reduced picture generating circuit 202 via information path 314. Reduced picture generating circuit 202 then generates a partially decoded reduced size picture 315 of decoded picture 313 in a manner similar to that as in the encoding device in order to re-write the contents of the picture stored in contracted picture storage circuit 204 and to enable a next recursive decoding step to start with partially decoded reduced picture 315. If the proper number of recursive decoding operations have taken place, and thus the duplicating operation has been carried out the predetermined number of times, reprocessing command information is sent by a decoded picture output control signal 311 to a switch 209. Switch 209 is controlled in order to couple a decoded picture 313 output from decoded picture storage circuit 208 to a picture output port 316. Decoded picture 313 comprises a conglomeration picture of all of the decoded blocks noted above after being recursively decoded for a predetermined number of iterations and is read out from decoded picture storage circuit 208 in accordance with control signal 312.
While this information encoding and decoding technique has been somewhat satisfactory, it has suffered from at least one major drawback. This drawback includes the encoding and decoding of an interlaced picture. An interlaced picture comprises a first field and a second field, which when combined in an alternating line-by-line basis generate a complete frame. This format is customary in television picture transmission. However, because of this interlaced scanning technique, it is very difficult to find similarity between various blocks of a frame, formed of portions from one field and portions from the other field, when objects within a series of interlaced pictures undergoes movement. That is, there is movement of a portion of one field relative to a portion from the other field. Thus, the picture quality is deteriorated and the encoding scheme performs less than optimal encoding.
Therefore, it would be beneficial to provide an improved encoding apparatus and method which overcomes the drawbacks of the prior art.